Currently, blood glucose monitoring after surgery is routinely used to evaluate the complete resection of insulinomas. However, there are prerequisites for the application of blood glucose levels: firstly, the preoperative blood glucose level must be low so that it is easier to observe the increasing change. Secondly, a portion of patients need intravenous glucose infusion to avoid life-threatening hypoglycemia, which would disturb the actual condition of endogenous blood glucose levels. Accordingly, under this circumstances, blood glucose monitoring could not be used for these patients. Therefore, the effectiveness of blood glucose levels is limited in acting as a parameter for evaluating the effect of complete resection of insulinomas.
As the aforementioned data demonstrated, the insulin level is relatively free from intravenous glucose infusion compared with the blood glucose level. In order to avoid severe hypoglycemia, patients with insulinoma can be treated with intravenous glucose infusion routinely before and during the operation without the worries of affecting the endogenous blood glucose level. Therefor it makes the insulin level more generally applicable to evaluating the complete resection of insulinoma.
Insulinomas are functional PanNETs automatically secreting insulin, and the insulin level can directly reflect the status of the tumor. The insulin level decreases sharply at 30 minutes after surgery and then it increases gradually, indicating that the insulin level was minimized within 30 minutes postoperatively. Compared with the insulin level, the response speed of the blood glucose level was relatively slower. The evaluating ability of the insulin level was better than that of the blood glucose level, both for the predictive accuracy and for response speed.
Previous studies have demonstrated that intraoperative insulin monitoring can reliably evaluate the complete removal of insulinomas(21, 30). However, these studies mainly described the application of insulin level. In our study, we compared the evaluating ability at multiple aspects between the blood glucose and insulin levels, confirming the superiority of insulin level in to blood glucose level.
The utility of insulin levels for evaluating complete resection of insulinoma is a trend. Perhaps insulin levels assayed less than 30 minutes after resection also have excellent predictive ability. It is possible to evaluate resection effectiveness earlier, which will be the next step of our study. The blood glucose level can be assayed within only 5 seconds. However, the test method of insulin level is more complicated than the blood glucose level. More convenient and rapid methods for testing insulin levels should be explored to allow for a broad range of applications, including for evaluating the complete resection of insulinoma.
About 10% insulinomas are with multiple leisions. We included insulinoma patients with single leision in this research in order to easily insure that the complete resection has been achieved definitely. Obtaining above-mentioned data, we are going to include insulinomas with multiple leisions in the further research, and study the effect of measuring the insulin level on evaluating the complete resection of multiple insulinomas.